The Dialer.Dial method returns an *http.Response on a bad handshake.
This CL updates the Dial method to include up to 1024 bytes of the
response body in the returned *http.Response. Applications may find the
response body helpful when debugging bad handshakes.
Fixes issue #62.
The Chrome debug server does not use case insensitive comparison on the
Connection header tokens as required by the HTTP RFC. Modify the client
to send "Connection: Upgrade" as expected by Chrome. Because this
matches the examples in the RFC, this change might improve
interoperability with other servers.